Design Ideal Ventilation Simple and Unique. Special ventilation holes in the house to live like a window, required at least 5 percent of the area of ​​the room. Wind flow is also influenced by the obstacles that are in the middle of the room. For example, the greater the furniture that stands between cross-ventilation, the more kinetic energy is also reduced and wind speed. Thus, avoid putting large objects between cross ventilation which can inhibit air circulation.